Online banks will force high-street branches in Europe to cut costs dramatically over the next three years, according to a study to be published by US investment bank JP Morgan on Monday.

The study indicates that the number of Europeans banking via the Internet will almost triple in the next three years to around 55m, reports the Financial Times.

This would make the online banking industry worth £275bn and would cost conventional banks an estimated £7bn in profits. The report concludes that Europe's largest banks will inevitably fight back with price cuts.

The biggest threat to bricks and mortar banks, says the report, is losing their most affluent customers to online competitors.